Best course of action depends on what's underneath the teak. I was lucky, there was a good, solid fiberglassdeck underneath mine, so I stripped off the teak, filled up the screw holes with epoxy, and then primed, painted the deck, and did a two-tone thing with some grit for the non skid areas. Looks fabulous, better than new.

But if you don't have fiberglass underneath, that complicates things. I'll let others talk about what they did in that case.

I'd try to find out what's underneath. If there's no fiberglass decking, it will be very expensive to fix, most likely. So consider that before getting serious about the boat.

I found it easier to cut the top layer of f/g with a skill saw and remove the f/g and teak at the same time. It's a real bitch taking off that teak. It was easier to lay up a new f/g deck. In my case, I found the core was saturated too so I replaced the core at the same time.